1. Technical Field of the Invention
The present invention relates in general to the transmission of data in a telecommunications network, and in particular to dynamically modifying the quality of service in connection with packet switched communications.
2. Description of Related Art
Initially, mobile telecommunications systems were designed primarily for purposes of enabling voice communications in a wireless environment. As wireless telecommunications systems have evolved, additional voice and messaging services and features have been added. In addition, newer generations of wireless telecommunications systems based on packet switched technology are being designed to handle an even more diverse range of data communications services. In contrast to analog and digital cellular protocols that are designed primarily for voice communications, these services allow for the transmission of large amounts of data at higher speeds than have previously been attainable, the possibility of maintaining a consistent connection to the network, and the ability to handle multimedia applications in an efficient way.
The end to end quality of service for a data. transmission is dependent upon the quality of service characteristics of the networks over which the data travels, such as the amount of bandwidth dedicated to the communication, the transfer delay, the reliability of the transmission (i.e., the error ratio), the traffic handling priority (e.g., a selection of which packets are dropped first if necessary), and the traffic class. In a public land mobile network (PLMN) that provides a packet transport service such as General Packet Radio Service (GPRS), for example, the transmission of data involves resources from both a packet switched core network and a radio network. As a result, the overall quality of service for a data packet transmission depends upon the quality of service provided by each of the packet switched core network and the radio network. The quality of service provided by the radio network is dependent on characteristics of the radio network, while the quality of service provided by the core network is dependent on the characteristics of the core network bearer.
When a data communication is initiated from a subscriber terminal, the subscriber requests a particular quality of service. The PLMN analyzes the request and, based in part on the availability of resources in the network, either provides the requested quality of service, proposes an alternative quality of service, or rejects the request. The subscriber terminal can accept or reject a proposed alternative quality of service or can renegotiate an alternative quality of service if the initial request was rejected.
If the PLMN cannot provide the initially requested quality of service due to congestion in either the radio network or the packet switched core network and the subscriber accepts a lower quality of service, the application that the subscriber wants to run might perform poorly. For example, the lower quality of service might result in slower transmission speeds or in a higher bit error rate. Unless the subscriber subsequently performs a manual upgrade of the quality of service at a time when a higher quality of service is available, any such inferior performance will continue for the duration of the communication session. As a result, the subscriber might run the application for long periods of time (e.g., hours) using a quality of service that is inferior to what he or she is entitled to use and is willing to pay for, even in cases where the PLMN""s congested state is alleviated shortly after the subscriber initiated the communication session.
The present invention comprises a method and system for upgrading and downgrading a quality of service that is provided by a packet-switched telecommunications network for communications involving a mobile user station. When a user station initiates a packet data communication session, the user station requests a certain quality of service. When the telecommunications network receives the request, the network attempts to allocate the requested quality of service for use during the communication session. If the network is congested, however, there might not be sufficient network resources available to be able to provide the requested quality of service. If the network detects such congestion, then an alternative quality of service can be assigned for use by the subscriber station, and the network can initiate a data communication session using that alternative quality of service.
During the communication session, the network monitors the level of congestion. In particular, the network attempts to identify an available quality of service that might be more attractive to the user for use during the ongoing communication session. Once the network identifies such an available quality of service, the network assigns the available quality of service for use by the subscriber station during the communication session. Preferably, the available quality of service is the same as the initially requested quality of service. As a result, the system is able to automatically upgrade or downgrade the quality of service offered to the user in accordance with the initial request.
In accordance with one embodiment of the invention, the network notifies the user station of the assignment of the alternative quality of service and, subsequently, of the availability of the potentially more attractive quality of service. The user is then able to accept or decline any assignment of an alternative quality of service and any modifications of the ongoing quality of service.
In accordance with another embodiment of the invention, the packet-switched telecommunications system comprises a radio network for communicating data packet signals with the user station and a core network for routing the data packets during the communication session. In response to the request for a data communication session, the radio network attempts to assign an appropriate radio access bearer service for use during the communication session, while the core network attempts to assign an appropriate core network bearer service for use during the communication session. If either the radio access bearer service or the core network bearer service cannot provide the requested quality of service, the system subsequently monitors congestion (i.e., after the packet session is established) in the networks to upgrade or downgrade the bearer services as appropriate so as to provide the requested quality of service.